A 'run-down area' is an area that has not been maintained
or fixed
the way it should. These places can be ugly and have
many broken
things. Notice the following:

The school looks pretty run-down now.

This town has turned into a really run-down area.

the norm

It was the norm for girls to get pregnant, leave school,
and then
come back again.

'The norm' is what is normal for a certain group of
people.
Notice the following:

What is the norm for the number of years to finish
school?

They generally follow the norm.

rough neighborhood

It was a rough neighborhood, a strange environment to be
in.

A 'rough neighborhood' is an area where the people are very
tough
and in many cases violent. There is usually a lot of
crime in
these parts and the people who live there are generally
poor.
Notice the following:

This used to be a rough neighborhood, but there have
been lots of
improvements.

She grew up in a really rough neighborhood.

keep out of trouble/get into trouble

It was hard to keep out of trouble, because everyone was
getting
into trouble.

To 'keep out of trouble' is to stay away from things or
decisions
that will cause you problems or to follow the rules.
When we 'get
into trouble' we don't follow the rules and somebody catches
us.
Notice the following:

I was surprised he kept himself out of trouble at
school.

He got into a lot of trouble when he was growing up.

no worries

[Thanks a lot.] No worries.

We can tell someone 'no worries' when something is not a
big
deal. Another way to say this is 'no problem' or
'don't worry
about it.' Notice the following: